1. Field of the Invention
The present invention relates generally to chemical mechanical polishing (CMP) technology, and more particularly, to a method of monitoring surface status and life of a pad by detecting temperature of a polishing interface during a CMP process.
2. Description of the Related Art
During the CMP process, abrasive slurry and pad are the primary expendable materials in direct connection with the manufacturing efficiency and yield. Although the abrasive slurry is non-reusable to cause no problem of operational life, the pad is frequently reusable during the CMP process to cause the problem of operational life. One pad may be used for polishing multiple wafers and then be reconditioned at its surface based on the surface status to remove residual chippings produced on surfaces of the wafers or residual abrasive particles from the surface of the pad. The pad is subject to gradual wear on its surface during the operation and recondition to reduce roughness of the surface and will be deserted while fully non-reusable.
As indicated above, the surface status and life of the pad is critical to the outcome of the CMP process. As currently on production line, the conventional method of monitoring the operational life of the pad is based on the experience of practical operation or the operational life provided by the supplier of the pad. However, the surface statuses of the pads during the CMP processes are not quite the same, such that there is a high probability that the pad is still reusable but deserted to cause operational waste or the abrasive is fully non-reusable but still reused to cause damage to the surface of the wafer, incurring resource waste and increasing cost.